Heater



FIG. 1 is perspective view of a heater incorporating my new design, viewed from in front of, above, and from the left side of the heater;

FIG. 2 is a side elevation view thereof, with the right side being a mirror image of the left side;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a rear elevation view thereof; and,

FIG. 6 is a bottom plan view thereof.

The broken lines in FIGS. 1-6 are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a heater, as shown and described. 